Development of resistance in Achatina fulica Fer. and Bradybaena similaris Fer. towards metaldehyde
S. Salmijah, M.K. Chan, B.H. Kong, A. Maimon and B.S. Ismail, School of Environmental and Natural Resource Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM, Bangi, Selangor, Malaysia.
The possible role of glutathione S-transferase (GST) in resistance to metaldehyde in two snails, Achatina fulica Fer. and Bradybaena similaris Fer. was investigated. Dose-response experiments (range 0-5%) of baited metaldehyde, showed 100% mortality of A. fulica to 5% metaldehyde within 24 hours. Dose response for B. similaris over the same range (0-5%) showed highest mortality of 60% at 2.85% metaldehyde, thereafter mortality decreased significantly. When 3% and 0.475% baited metaldehyde were given repeatedly to A. fulica and B. similaris respectively, mortality rates decreased significantly; concomitant with increases in GST activities in both the snails. In B. similaris, ELISA assays showed progressive increases in GST concentrations (P<0.05) for each consecutive metaldehyde treatment. There was also positive correlation (r=0.97) between specific activities of GST to the intensities of signals for the GST protein as determined by Western and densitometric analyses. These latter observations suggest the synthesis of new GST in B. similaris to cope with higher metaldehyde concentrations in its tissues.
Plant Protection Quarterly (2000) 15 (1) 2-5.